更换按钮位置

Question

l我的C＃winform项目有问题。

在我的项目中，我有一个功能，可以将按钮的位置切换到原来的位置，如果它们在同一个区域。

私人无效myText_MouseUp（对象发件人，发送MouseEventArgs E） {

Point q = new Point(0, 0); 
     Point q2 = new Point(0, 0); 
     bool flag = false; 
     int r = 0; 
     foreach (Control p in this.Controls) 
     { 
      for (int i = 0; i < counter; i++) 
      { 
       if (flag) 
       { 
        if (p.Location.X == locationx[i] && p.Location.Y == locationy[i]) 
        { 
         oldx = e.X; 
         oldy = e.Y; 
         flag = true; 
         r = i; 
        } 
       } 
      } 
     } 
     foreach (Control p in this.Controls) 
     { 
      for (int j = 0; j < counter; j++) 
      { 
       if ((locationx[j] == p.Location.X) && (locationy[j] == p.Location.Y)) 
       { 
        Point arrr = new Point(oldx, oldy); 
        buttons[j].Location = arrr; 
        buttons[r].Location = new Point(locationx[j], locationy[j]); 
       } 
      } 
     } 
} 
    The problem with this code is that if they are in the same area, the buttons do not switch their locations. Instead they goes to the last button location. 

如果有人可以帮助我，这将帮助我很多:)

Answer 1

的if语句总是判断为真。这意味着，最终j循环会做到这一点：

// last time round the i loop, i == counter-1 
// and q == new Point(locationx[counter-1], locationy[counter-1]) 
for (int j = 0; j < counter; j++) 
{ 
    Point q2 = new Point(locationx[j], locationy[j]); 
    buttons[i].Location = q2; 
    buttons[j].Location = q; 
} 

这样做的最终结果是，每一个按钮的Location设置为q，这是

new Point(locationx[counter-1], locationy[counter-1]) 

---

为什么会出现if声明始终评估为true。那么，首先让我们来看看一对夫妇的or条款在if声明：

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 
|| ((q.Y >= q2.Y) && (q.X == q2.X)) 

这相当于

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 

含==测试线路已最终完全没有影响条件的结果。实际上所有包含==的行都可以进行类似的处理。这使得：

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 
|| ((q.Y >= q2.Y) && (q.X >= q2.X)) 
|| ((q.Y <= q2.Y) && (q.X >= q2.X)) 
|| ((q.Y <= q2.Y) && (q.X <= q2.X)) 

我们可以凝聚

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 
|| ((q.Y >= q2.Y) && (q.X >= q2.X)) 

到

|| ((q.Y >= q2.Y) 

，同样

|| ((q.Y <= q2.Y) && (q.X >= q2.X)) 
|| ((q.Y <= q2.Y) && (q.X <= q2.X)) 

相同

|| ((q.Y <= q2.Y) 

结合

|| ((q.Y >= q2.Y) 
|| ((q.Y <= q2.Y) 

，你可以看到if条件始终计算为true。